Molybdenum powder has been plasma sprayed on stainless steel, brass and aluminum substrates. The substrate melting phenomenon is observed and investigated by means of scanning electron microscopy (SEM) and scanning white light interferometery (SWLI). It is found that the flower-shape splat morphology is typical for molybdenum on all three substrate materials when the substrate is at room temperature. Notable substrate melting is manifested through the energy dispersion analysis of X-ray (EDAX) map and Robinson back-scattered image of cross-sections of splats. It has been shown that the substrate material plays an important role in substrate melting phenomenon. The lift angle of the petals of splats and the maximum crater depth have been characterized and compared. Both of these increase in the sequence, from stainless steel, brass to aluminum. A ‘volume of fluid’ (VOF) based model coupled with rapid solidification has been used to simulate splat deformation, solidification, substrate melting and resolidification. The numerical & analytical results agree quite well with the experimental data. A substrate melting mechanism is proposed based on the time scales of the droplet solidification and substrate melting to explain the formation of flower like splat morphologies.

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